Heat exchangers are known for transferring heat from a first medium to a second medium. In one example, the heat exchanger may be positioned within an exhaust conduit of an internal combustion. Heat from the exhaust gases produced by the internal combustion engine may be transferred to another medium which may be used, for example only, to elevate the temperature of the air going to the passenger compartment of the motor vehicle for passenger comfort, to warm batteries of hybrid electric motor vehicles which use batteries to store electrical energy to provide or assist in propulsion of the hybrid electric motor vehicle under certain conditions, to warm powertrain fluids of the motor vehicle in order to reduce viscosity of the powertrain fluids, thereby reducing friction and improving fuel economy, or to cool exhaust gases that may be recirculated back into the internal combustion engine.
United States Patent Application Publication No. US 2008/0223024 A1 to Kammler et al. shows an example of such a heat exchanger for cooling exhaust gases produced by an internal combustion engine. The heat exchanger of Kammler et al. includes a plurality of tubes which allow passage of the exhaust gas therethrough. Each of the plurality of tubes passes through a coolant jacket and a liquid coolant is circulated through the jacket. In order to form the coolant jacket, each tube is sealed by welding to a portion of the water jacket. Such a heat exchanger may be difficult and costly to manufacture due to the need to align and seal each tube with a corresponding hole in the water jacket. Furthermore, heat transfer from the exhaust gases to the coolant may be less than satisfactory.
U.S. Pat. No. 6,293,337 to Strähle et al. shows another example of such a heat exchanger for transferring heat from exhaust gases produced by an internal combustion engine to a water coolant. The heat exchanger of Strähle et al. includes a stack of heat exchanger plates through which the water coolant is circulated. The heat exchanger plates are separated by flow channels through which the exhaust gases are passed. The flow channels may include features therein to improve heat exchange with the water coolant in the heat exchanger plates. The heat exchanger plates are connected to each other by collection spaces. The flow channels pass through the collection spaces, and therefore must be sealed from the collection spaces in order to prevent the water coolant from escaping. Such a heat exchanger may be difficult and costly to manufacture due to the need to align and seal each flow channel with corresponding holes in the collection spaces.
What is needed is a heat exchanger which minimizes or eliminates one or more of the shortcomings as set forth above.